The present invention relates generally to damper assemblies, and in particular, relates to a latch usable in combination with a damper that, when installed within the ductwork of a building, strengthens the seal provided by the damper blades when the damper is closed.
Building and fire codes require that dampers be placed in specified heating, ventilation, and air conditioning ducts. Dampers include a pair of damper blades that operate in a normally open position, which allows air to flow through the ductwork. The blades can close to prevent air flow through the ductwork in response to a predetermined stimulus. The stimulus can be a dramatic increase in temperature, indicating a fire or other hazardous condition, or any other event that causes the damper blades to close.
Conventional damper blades are biased towards their closed position by a spring member or the like, but held open by a fusible link or other suitable member that prevents the blades from closing under the spring force. When the fusible link fails in a predetermined manner in response to an elevation in temperature, the mechanical interference maintaining the blades in their open position is removed, and the damper closes to form a seal with the duct with respect to airflow. As a result, airflow throughout the building is minimized in response to a fire or other hazardous condition.
It should be appreciated that the ability for the damper to prevent the hazardous material or fire from spreading throughout the building depends largely on the strength of the seal between the damper blades and the ductwork when the blades are closed. A damper becomes “fire-rated” by Underwriters Laboratories if it is able to withstand the extreme temperatures for a predetermined amount of time without weakening its seal between the blades and the duct. In conventional dampers, prolonged exposure to extreme temperatures associated with heat tend to weaken the damper components and the resulting seal.
What is therefore needed is a damper assembly capable of providing an enhanced seal between the damper blades and the duct with respect to conventional damper assemblies.